This is pretty much what I would recommend. The Q150 is a coaxial speaker, so it doesn't really care whether it is sitting upright or sideways. The only downside with the Q150 is the lack of midbass punch, due to the small woofer surface area.
Something like the Q250c is basically a Q150 just with passive radiators instead of a port, so if you are placing it up against a wall it may be better. It will probably have similar midbass performance to the Q150.
If 3x Q250c are too much, then 2 of them will be fine, though having a dedicated center channel is obviously preferred.
No matter what, speakers that small are going to have issues reaching even an 80hz crossover, unless you have a very small room or listen at low levels.
I would avoid using bookshelf speakers on their side or other traditional center speakers (say like the Klipsch RP-500c) as their 2-way design, and non-coaxial layout cause issues when listening off-axis (different seats get a wildly different sound).
So if the Q150 / Q250 are too big:
Kef also made something smaller (
link to a review to get you started), but you would need to look somewhere like Ebay to find them now.
If you must buy new, given these constraints, I honestly would recommend a good soundbar. Having an AV receiver with fancy room correction and such doesn't do you any good if you don't also have good speakers. Nobody really makes good speakers I would recommend for a home theater application in the size constraints you have.
The truth of the matter is that despite all the hate they get, soundbars are still a good option to get quality sound in a small package.
It looks like you have a Sony TV, so if it is a modern one it may have special integration options for a Sony soundbar, and I also know that Samsung's soundbars are pretty good.
I wouldn't recommend a passive soundbar. Ones with built-in processing and amplification can correct for their speakers much more effectively than trying to use an AVR's room correction to do it. They also can have features like beamforming and such that enable fancy surround experiences (Though I have never heard it so YMMV).